JP2001221851A - Ultrasonic sensor apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily discriminate a reflected wave with respect to noise and to expand a measuring range of an approach distance. SOLUTION: A controller 10 is equipped with a microcomputer 20 for outputting an oscillation pulse signal (a) to a signal line 39 via a modulation transistor 18 and inputs the reflected wave signal f', obtained by passing the receiving signal from the sensor part 40A through a detector 33 to detect obstacles or the like. In the sensor part 40A, an ultrasonic microphone 42 is driven by an output circuit 50, to send out an ultrasonic wave and the signal d' obtained through amplification a receiving signal c' by an antilogarithmic amplifier 60 is outputted to the signal line. The input side of the antilogarithmic amplifier is grounded by a prescribed time, containing the drive pulse of the ultrasonic microphone by a transistor 65 to be attenuated. Since reflected waves are amplified to the same level, regardless of the distance up to the obstacle or the like by the antilogarithmic amplifier, even if noise is mixed from the signal line, the discrimination of reflected waves is easy and the reverbration of the ultrasonic microphone is shortened by attenuation duet to the transistor 65 and a detectable distance becomes shorter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic sensor device mounted on a vehicle and used for detecting obstacles around the vehicle.

[0002]

2. Description of the Related Art An ultrasonic sensor device transmits an ultrasonic wave from a transmitter, receives a reflected wave from an object by a receiver, and detects a distance to the object based on a time difference from transmission to reception. . Using this for a vehicle, as an alarm is issued when the detected obstacle is within a predetermined distance,
There is such as shown in FIG. This is composed of a sensor unit for transmitting and receiving an ultrasonic wave and a controller for controlling the same, and a buzzer is driven by an output of the controller to generate an alarm. FIG. 5 shows a signal waveform in each section.

[0003] The controller 10 has a power supply terminal 11 connected to the battery 1 via the ignition switch 2;
An output terminal 13 connected to the buzzer 3 and a first control communication terminal 12 connected to the sensor unit 40 are provided, and a microcomputer 20 is provided inside. Microcomputer 2
0 is operated by the constant voltage source 14 connected to the power supply terminal 11 and outputting 5V. From the oscillation output terminal 22, 40
A KHz oscillation pulse signal a is output, a reflected wave signal f is input to an input terminal 21, and a buzzer drive signal is output from a drive output terminal 23 based on the time difference.

A modulation transistor 18 is provided between the power supply terminal 11 and the control terminal 12.
The collector of 8 is connected to the power supply terminal 11, and the emitter is connected to the first control communication terminal 12 via the resistor 19. The base connected to the collector via the resistor 30 is
It is connected to the collector of the control transistor 16 via a zener diode 17. The base of the control transistor 16 is connected to the oscillation output terminal 22 of the microcomputer 20 via the resistor 15, and the emitter is grounded.

The modulation transistor 18 is normally turned on, and a signal b0 obtained by modulating a voltage input to the power supply terminal 11 by an oscillation pulse signal from the microcomputer 20 via the control transistor 16 is used as a first control communication terminal. Give to 12.

An amplifier (AMP) 32, a detector 33 and a comparator 34 are sequentially connected to the first control communication terminal 12 via a capacitor 31.
4 is the input terminal 21 of the microcomputer 20
It is connected to the. A drive transistor 3 is connected to a drive output terminal 23 of the microcomputer 20 via a resistor 35.
6, the base of the driving transistor 36 is connected to the output terminal 13, and the emitter is grounded. The buzzer 3 is connected between the power terminal 11 and the output terminal 13.

[0007] The sensor unit 40 is a first
The control communication terminal 12 includes a second control communication terminal 41 connected to the control communication terminal 12 via a signal line 39, and an ultrasonic microphone 42 including a piezoelectric element. The ultrasonic microphone 42 also serves as an ultrasonic transmitter and a reflected wave receiver. The ultrasonic microphone 42 is connected between the second control communication terminal 41 and the ultrasonic microphone 42 based on a signal received from the controller 10 to the second control communication terminal 41.
An output circuit 50 for generating a drive pulse to the drive circuit is provided. Between the ultrasonic microphone 42 and the second control communication terminal 41, an amplifier 90 and a bandpass filter 80 for a reflected wave received by the ultrasonic microphone 42 are further provided.

The output circuit 50 mainly includes transistors 51 and 52 and a transformer 58 connected in series, and the emitter of the transistor 51 has a capacitor 54 whose one end is grounded.
Is connected to the second control communication terminal 41 via a diode 53. The base of the transistor 51 is connected to the second control communication terminal 41 via the resistor 55.
It is connected to the.

The base of the transistor 52 is also connected to the second control communication terminal 41 via the resistor 56, and the emitter is grounded. A connection point between the collector of the transistor 51 and the collector of the transistor 52 is connected to a primary side of a transformer 58 via a capacitor 57, and a secondary side of the transformer 58 is connected to the ultrasonic microphone 42.

The amplifier 90 is composed of a differential amplifier 91 which inputs a reception signal of the ultrasonic microphone 42 to an inverting input section and connects an output section and an inverting input section via a resistor 92. To amplify.

The band-pass filter 80 outputs the output of the amplifier 90 to a capacitor 81, a resistor 82, and a capacitor 83.
And a differential amplifier 84 connected between the output unit and the inverting input unit via a resistor 85. The connection point between the resistor 82 and the capacitor 83 is grounded via a resistor 86, and a capacitor 87 is further provided between the resistor 82 and the output of the differential amplifier 84. This allows
The band-pass filter 80 is set to pass only a signal having a predetermined width centered on 40 KHz.

An amplifier 90 and a bandpass filter 80
A non-inverting input of each differential amplifier 91, 84 is applied with a bias voltage formed by a resistor 71, a Zener diode 72, and a capacitor 73 connected to the second control communication terminal 41 via a diode 53. . A capacitor 75 and a resistor 76 are provided between the ultrasonic microphone 42 and the amplifier 90, and a capacitor 77 is provided between the band-pass filter 80 and the second control communication terminal 41 to cut off DC. .

In the sensor section 40, an output circuit 50 outputs transistors 51 and 5 based on a signal from the controller 10.
2 alternately repeats on / off to generate a drive pulse c0, thereby driving the ultrasonic microphone 42 to transmit ultrasonic waves. When the ultrasonic microphone 42 receives a reflected wave that has returned after hitting an obstacle or the like, the reflected waves c1, c2,
After the received signal cR including c3 is amplified by the amplifier 90,
The signal is output to the signal line 39 connected to the second control communication terminal 41 via the band pass filter 80. Note that c1, c
2 and c3 are reflected waves from obstacles and the like at different distances.

In FIG. 5, dR (d1, d2, d3) is a received signal corresponding to the reflected wave amplified by the amplifier 90. The drive pulse c is limited by the limitation of the operating voltage of the amplifier 90.
The amplified signal d0 of 0 has a predetermined maximum amplitude. FIG.
B, excluding b0, bz, bR (b1, b2, b
3) is a signal output on the signal line 39 via the band pass filter 80.

In the controller 10, after the received signal d on the signal line 39 is amplified by the amplifier 32, detection is performed by the detector 33. The comparator 34 limits the detection signal e to a signal having a predetermined strength L or more, shapes the waveform, and adjusts the reflected wave signal fR
Output as (f1, f2, f3). The microcomputer 20 performs a predetermined calculation based on the reflected wave signal fR output from the comparator 34 and the previously output oscillation pulse signal a, and obtains a distance to an obstacle or the like.

According to the ultrasonic sensor device as described above, transmission and reception of ultrasonic waves are performed by a single ultrasonic microphone 42, so that the size is reduced and the cost is reduced. Since the power supply line also serves as the power supply line for the unit 40, there is an advantage that the configuration can be simplified.
Further, various applications have been proposed, such as not only obstacle detection but also measurement of a distance between a vehicle floor and a road surface, for example.

[0017]

However, in the above-mentioned conventional apparatus, the controller 10 and the sensor section 40 are separated from each other and are connected by a signal line 39. Through which noise is likely to be mixed. On the other hand, the reflected wave reception signal in the sensor unit 40 is weaker as the distance to the obstacle is longer, and the reception voltage sequentially decreases as c1, c2, and c3, and the amplifier 90 simply converts the reception signal at a constant amplification factor. Since the signal is only amplified in proportion, the reflected wave from a long distance is buried in noise, and there is a problem that it is difficult to identify the reflected wave.

An ultrasonic microphone 4 using a piezoelectric element or the like
No. 2 has a problem that reverberation cz is accompanied when this is driven. Since the single ultrasonic microphone 42 is also used for transmitting and receiving ultrasonic waves, the reverberation component is also amplified like dz and then input to the controller 10 as bz on the signal line. In the measurement of a close distance such as a road surface, the reflected wave may overlap with the reverberation component dz, which may make identification difficult. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an ultrasonic sensor device capable of easily identifying a reflected wave with respect to noise and expanding a measurement range of a close distance in view of the above problems.

[0019]

According to the present invention, there is provided an ultrasonic sensor device for transmitting and receiving ultrasonic waves by a single ultrasonic transmitting and receiving body, detecting reflected waves, and detecting the presence of an object. In addition, it is configured such that a reception signal received by the ultrasonic transmitter / receiver is amplified by an antilogarithmic amplifier and then a reflected wave detection process is performed. The antilogarithmic amplifier amplifies the reflected wave from a short distance and the reflected wave from a long distance to the same level of amplitude, so that when the subsequent detection processing is performed at a remote site via the signal line, for example, noise from the signal line is reduced. However, any reflected wave can be easily identified without being buried in noise.

According to a second aspect of the present invention, the reception signal attenuating means which operates for a predetermined time including the supply of the driving pulse to the ultrasonic transmitter / receiver is provided on the reception signal input side of the antilogarithmic amplifier. The receiving signal attenuating means connects a transistor between the receiving signal input side of the antilogarithmic amplifier and the ground, and connects the base of the transistor to an operating power supply comprising a capacitor charged by a driving pulse. Can be configured. By the operation of the reception signal attenuating means, the reverberation following the driving of the ultrasonic transmitting and receiving body is quickly eliminated, and the reflected wave from a close distance can be detected without overlapping the reverberation.

[0021]

Next, embodiments of the present invention will be described with reference to examples. FIG. 1 is a diagram showing the configuration of the embodiment. FIG. 2 shows a signal waveform in each section. The controller 10 and the buzzer 3 connected thereto are the same as the controller and the buzzer in the conventional device shown in FIG.

The sensor section 40A includes a second control communication terminal 41 connected to the first control communication terminal 12 of the controller 10 via a signal line 39, and an ultrasonic microphone 42 composed of a piezoelectric element. An output circuit 50 is provided between the second control communication terminal 41 and the ultrasonic microphone 42 for generating a drive pulse for the ultrasonic microphone 42 based on a signal received from the controller 10 to the second control communication terminal 41. I have. Output circuit 50
Is the same as the output circuit in the conventional device shown in FIG. 4, and the secondary side of the transformer 58 is connected to the ultrasonic microphone 42.

An antilogarithmic amplifier 60 and a bandpass filter 80 are sequentially connected to the ultrasonic microphone 42 via a series capacitor 75 and a resistor 76.
Is connected to the second control communication terminal 4 via the capacitor 77.
1 connected.

The antilogarithmic amplifier 60 includes a differential amplifier 61 whose output is connected to an inverting input section via a resistor, and a transistor 63 is provided between the inverting input section and a resistor 76. The transistor 63 has a collector connected to the differential amplifier 61.
, The emitter is connected to the resistor 76, and the same bias voltage as that of the non-inverting input section is applied to the base. Thereby, as shown in FIG. 3, the antilogarithmic amplifier 60 has a high output voltage when the input voltage is small,
When the input voltage is large, the output voltage is low.

Transistor 6 in antilog amplifier 60
The emitter of 3 is further grounded via transistor 65. The base of the transistor 65 is connected to a connection point between the transistor 51 and the transistor 52 in the output circuit 50 via a resistor 66, and is also grounded via a resistor 67 and a capacitor 68 which are parallel to each other.

The bandpass filter 80 is the same as the bandpass filter in the sensor section of the conventional device shown in FIG. Antilog amplifier 60 and bandpass filter 80
A bias voltage formed by a resistor 71, a Zener diode 72 and a capacitor 73 connected to the second control communication terminal 41 via a diode 53 is applied to the non-inverting input portions of the differential amplifiers 61 and 84. I have.

In the above configuration, in the sensor section 40A,
In the output circuit 50, the transistors 51 and 52 alternately turn on and off based on a signal from the controller 10 to generate a drive pulse c0, thereby driving the ultrasonic microphone 42 to transmit ultrasonic waves. When the ultrasonic microphone 42 receives the reflected wave that has returned after hitting an obstacle or the like, the received signal cR including the reflected wave is converted into an antilogarithmic amplifier 60.
, And is output to the signal line 39 connected to the second control communication terminal 41 via the band pass filter 80.

A received signal having a small input voltage is greatly amplified by the antilogarithmic amplifier 60, and a received signal having a large input voltage is amplified by the antilogarithmic amplifier 60 to be slightly amplified.
The subsequent received signals have the same level of amplitude as dR '(d1', d2 ', d3'). Output circuit 5
0 outputs the driving pulse c0, the electric charge is stored in the capacitor 68, and the base potential of the transistor 65 is increased to turn on the transistor 65.
The input of the received signal to is attenuated.

Since the capacitor 68 is gradually discharged after the drive pulse c0 is turned off, the terminal potential of the capacitor 68 is maintained at a predetermined value or more for a while after the drive pulse c0 is turned off, and the transistor 65 is kept on. As a result, the energy of the reverberation component dz ′ of the ultrasonic microphone 42 following the amplified signal d0 ′ of the drive pulse is attenuated, and d
It disappears in a time shorter by W than the length of z. In FIG. 2, b
z ′ and bR ′ (b1 ′, b2 ′, b3 ′) are signals output on the signal line 39 via the band-pass filter 80. Further, e ′ and fR ′ (f1 ′, f2 ′, f
3 ′) are a detection signal for the signal b ′ on the signal line 39 and a reflected wave signal extracted by the comparator 34, respectively.

The present embodiment is configured as described above. In the ultrasonic sensor device in which a sensor unit 40A for transmitting and receiving ultrasonic waves by a single ultrasonic microphone 42 and a controller 10 for controlling the same are connected by a signal line 39. Since the sensor unit 40A amplifies the reception signal of the ultrasonic microphone 42 with the antilogarithmic amplifier 60 and then outputs the signal to the controller 10 for detection, the reflected wave from a short distance and the reflected wave from a long distance are at the same level. , And even if noise is mixed in from the signal line 39, it is easy to identify, and the detection of an obstacle or the like is reliably performed.

The receiving signal input side of the antilogarithmic amplifier 60 is grounded via a transistor 65, and the ultrasonic microphone 42
A predetermined time including the supply of a drive pulse to the transistor 6
By turning on 5, the time for eliminating the reverberation following the driving of the ultrasonic microphone is reduced, so that the region where the reflected wave overlaps with the reverberation and cannot be identified is reduced, and the reflected wave from a closer distance than before can be detected. . The predetermined time can be easily adjusted by selecting the capacitance of the capacitor 68 included in the power supply connected to the base of the transistor 65.

In the embodiment, the ultrasonic microphone 42 composed of a piezoelectric element is used as a single ultrasonic transmitter / receiver, but various alternatives can be used. Further, the buzzer 3 is operated by the drive output of the controller 10, but the invention is not limited to this. The buzzer 3 may be visually displayed to indicate the distance to a reflective object such as an obstacle.

[0033]

As described above, according to the first aspect of the present invention, in an ultrasonic sensor device using a single ultrasonic transmitter / receiver, a signal received by the ultrasonic transmitter / receiver is amplified by an antilog amplifier. Since the detection processing of the reflected wave is performed, the reflected wave from a short distance and the reflected wave from a long distance are amplified to the same level of amplitude, so that even if noise is mixed, any reflected wave can be obtained. It can be easily identified without being buried in noise. Therefore, even when the sensor unit including the ultrasonic transmitting / receiving unit and the other detection processing side are installed at a distance from each other and are connected via the signal line, there is no influence from noise that may be on the signal line.

According to the second aspect of the present invention, the reception signal attenuating means is further provided on the reception signal input side of the antilogarithmic amplifier and is operated only for a predetermined time including the supply of the driving pulse. The detection area of the close distance is expanded. According to a third aspect of the present invention, the reception signal attenuating means is provided by grounding a reception signal input side of an antilogarithmic amplifier via a transistor having a base connected to an operating power supply comprising a capacitor charged by a drive pulse to the ultrasonic transmitter / receiver. So,
The predetermined time can be set with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing signal waveforms at various parts of the embodiment device.

FIG. 3 is a diagram illustrating gain characteristics of an antilog amplifier according to an embodiment.

FIG. 4 is a diagram showing a conventional example.

FIG. 5 is a diagram showing a signal waveform in each section of the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery 2 Ignition switch 3 Buzzer 10 Controller 11 Power supply terminal 12 First control communication terminal 13 Output terminal 14 Constant voltage source 15, 19 Resistance 16 Control transistor 17 Zener diode 18 Modulation transistor 20 Microcomputer 21 Input terminal 22 Oscillation output terminal 23 Drive output terminal 30 Resistance 31 Capacitor 32 Amplifier 33 Detector 34 Comparator 35 Resistance 36 Drive transistor 39 Signal line 40 Sensor unit 40A Sensor unit 41 Second control communication terminal 42 Ultrasonic microphone 50 Output circuit 51, 52 Transistor 53 Diode 54 Capacitor 55 , 56 resistor 57 capacitor 58 transformer 60 antilogarithmic amplifier 61 differential amplifier 62, 66, 67 resistor 63, 65 transistor 68 capacitor 71, 76 Anti 72 Zener diode 73 capacitor 75, 77 capacitor 80 bandpass filters 81,83,87 capacitor 82,85,86 resistor 84 differential amplifier 90 amplifier 91 differential amplifier 92 resistors

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J083 AA02 AB13 AC05 AC16 AC18 AD04 AE01 AE06 AE08 AF05 BA01 BE50 BE54 CA01 CB01 CC03 EB11

Claims (3)

[Claims] An ultrasonic sensor device for transmitting and receiving an ultrasonic wave by a single ultrasonic transmitting / receiving body and detecting a reflected wave to detect the presence of an object, wherein the reception signal received by the ultrasonic transmitting / receiving body is antilogarithmic. An ultrasonic sensor device configured to perform reflected wave detection processing after being amplified by an amplifier. 2. A reception signal attenuating means which operates for a predetermined time including supply of a driving pulse to said ultrasonic transmission / reception unit is provided on a reception signal input side of said antilogarithmic amplifier. The ultrasonic sensor device according to claim 1. 3. An operation power supply comprising a transistor connected between a reception signal input side of the antilogarithmic amplifier and a ground, wherein a base of the transistor is charged by the drive pulse. The ultrasonic sensor device according to claim 2, wherein the ultrasonic sensor device is connected to the ultrasonic sensor.